Field of the Invention
The present invention relates to an image display apparatus and a method of controlling the image display apparatus.
Description of the Related Art
In an image display apparatus, brightness unevenness and color unevenness appear on a screen due to the characteristics of a display panel and the structure of the image display apparatus. In an image display apparatus such as a liquid-crystal display (LCD) apparatus that displays an image on a screen using light emitted from a light-emission unit, brightness unevenness and color unevenness appear on the screen due to the characteristics of the light-emission unit (backlight).
For example, the brightness unevenness appearing on the screen of the image display apparatus is that brightness reduces from the center to the end of the screen. Note that the brightness unevenness is not limited to this but may appear in various ways depending on the characteristics of the display panel, the structure of the image display apparatus, the characteristics of the light-emission unit, or the like.
Technology for reducing the unevenness of the screen is disclosed in, for example, Japanese Patent Application Laid-open No. 2007-114427.
In the technology of Japanese Patent Application Laid-open No. 2007-114427, each gradation value of an input image is corrected such that the brightness of each position of the screen coincides with the brightness of the end (the position having the lowest brightness) thereof.
According to the technology disclosed in Japanese Patent Application Laid-open No. 2007-114427, however, the brightness of each position of the screen is reduced such that the brightness of each position of the screen coincides with the brightness of the end thereof. Therefore, the reduction in the brightness unevenness of the screen results in reduction in the brightness of the entire screen, whereby the dynamic range of a display image (image displayed on the screen) is reduced.
Technology for suppressing the reduction in the brightness of the screen due to the reduction in the unevenness is disclosed in, for example, Japanese Patent Application Laid-open No. 2008-310261.
In the technology of Japanese Patent Application Laid-open No. 2008-310261, each gradation value of an input image is corrected with a smaller correction amount when a color component is larger in intensity. Therefore, the reduction in the brightness of the screen due to the reduction in the unevenness may be suppressed with a higher suppression degree when a color component is larger in intensity.
According to the technology disclosed in Japanese Patent Application Laid-open No. 2008-310261, however, each gradation value of an input image is corrected with a smaller correction amount when a color component is larger in intensity. Therefore, when each gradation value of the input image is large, the unevenness may not be reduced with high accuracy.